The present invention relates generally to a crash testing apparatus and, more particularly, to device capable of simulating one or both of pre-impact conditions and vehicle crash conditions.
In the design of vehicles and their safety restraint systems it is desirable that the occupant sustain minimal injury during a crash event. This focus on occupant safety has resulted in the creation of various safety restraint systems and crash testing methods. As will seen from the discussion below, current testing methodologies do not account for xe2x80x9cpre-impactxe2x80x9d events. This is accomplished by the present invention.
Typically, before a vehicle crashes, two scenarios usually exist. Either the driver of the vehicle applies the vehicle brakes in anticipation of the crash or the vehicle collides with some smaller obstacle such as a curb before colliding into a larger object. The result of either of these two scenarios is the generation of a pre-impact force or acceleration on the vehicle occupant. This pre-impact force and the kinematics which follow cause the occupant to move from his or her pre-impact seated position to a modified position. This movement may be characterized by the occupant pivoting or sliding forward which may result in a reduction of the normal force and frictional forces acting between the occupant and the seat. This position is referred to as a xe2x80x9cpre-impact positionxe2x80x9d. This pre-impact re-positioning could place the occupant in a more vulnerable out-of-position orientation immediately prior to the actual vehicle collision. As a result, this phenomena may contribute to greater injuries sustained by the occupant.
In an attempt to understand crash conditions and test new safety designs, various methods and devices have been constructed and used to simulate a vehicle crash. One such method is sled testing. In sled testing, a sled with a crash test dummy is accelerated to simulate the actual crash pulse which would occur for a particular vehicle. Every aspect of this crash testing is designed to simulate, as close as possible, the actual conditions associated with a vehicle crash. In these prior test systems the test sled is either accelerated rearward at a level to match the deceleration of the vehicle crash (pulse) or the sled is accelerated forward and stopped at a proper deceleration level to match the vehicle crash pulse. In each of these test methodologies, the simulated occupant, that is, the crash dummy, is positioned in a predetermined static seating position relative to the seat carried by the test sled.
These previous crash testing methods, however, have not accounted for the effect of pre-impact conditions on the occupant for several reasons. For example, the operator of a moving vehicle may apply the brakes for many seconds before actual impact. To simulate this pre-impact activity the testing sled would have to be moved a great distance and be decelerated over a long period of time. The present invention is designed to overcome this drawback.
The present invention provides a method and device for simulating both pre-impact and impact conditions. The device includes a test sled, a simulated occupant, that is, a crash dummy, and a pre-impact force-generating device. The pre-impact forces are applied directly to the simulated occupant or the occupant compartment (or part thereof) rather than to the entire test sled, thereby overcoming many of the cost and logistical problems associated with applying a low-level, long-duration pre-impact force directly to a test sled. The pre-impact force-generating device can be designed such that instead of providing a low-level, long-duration force, it provides a short-duration and high-level impact force. To simulate crash conditions, a crash impact force-generating device provides an impact force directly to the sled which simulates the impact or crash event.
Additional advantages and features of the present invention will become apparent from the subsequent description and the appended claims taken in conjunction with the accompanying drawings.